Blog

When to Plant Peas in Phillips County, MT

Peas are a cool-season legume that fixes nitrogen in the soil. Garden peas are shelled, while snap and snow peas are eaten pod and all.

Phillips County, Montana is in USDA Zone 4a. The average last spring frost is May 18 and the first fall frost is September 21, giving you a growing season of approximately 126 days.

At an elevation of 6,886 feet, Phillips County receives approximately 19 inches of rainfall annually with predominantly loam soil. Summer highs average 80ยฐF, so choose short-season varieties of Peas to ensure they mature before fall. With low rainfall, drip irrigation is essential for growing Peas successfully. Mulch heavily to conserve soil moisture.

Phillips County, MT (Zone 4a) Short season
126 days
Last Spring Frost May 18
126 growing days
First Fall Frost September 21

Phillips County Soil Profile

Soil Type

Loam

Soil pH

6.7-7.6

Drainage

Well Drained

Plant Planting Risk Windows

Early Start (70% safe) ✓ Fits season (12 days to spare)
Start indoors: Mar 31 Transplant: May 12 🍅 Harvest: Jul 7 – Sep 1
Recommended (50%) ✓ Fits season (14 days to spare)
Start indoors: Apr 6 Transplant: May 18 🍅 Harvest: Jul 13 – Sep 7
Safe Start (90%) ✓ Fits season (15 days to spare)
Start indoors: Apr 19 Transplant: May 31 🍅 Harvest: Jul 26 – Sep 20

Percentages indicate frost risk at transplant. The 70% safe window means there is a 30% chance of frost after transplant — suitable for cold-hardy crops or gardeners with frost protection. The 90% safe window is best for tender plants.

Soil Compatibility in Phillips County

How your county's soil matches Peas's growing requirements.

Soil pH

Your soil pH (6.7โ€“7.6) overlaps with Peas's range (6.0โ€“7.5), though not a perfect match.

Soil Texture

The loam soil in Phillips County is excellent for Peas โ€” good drainage, moisture retention, and nutrient holding capacity.

Organic Matter

Organic matter is moderate (2.4%). Annual compost additions will help Peas.

How to Plant Peas

1"
Planting Depth
4"
Between Plants
18"
Between Rows

Fall planting: Sow 12 weeks before your first frost date for a fall harvest.

Succession Planting Peas

2
successive plantings in your 126-day season

Sow every 6.3 weeks. Last sowing by Jul 13 to harvest before frost.

For a dedicated fall crop, sow by Jun 29.

Plant Water Budget

Plant needs
0.7″/week
Rainfall provides
0.6″/week
You supply
0.1″/week
Watering frequency Only during dry spells
Season total 90 gal / 100 sq ft
Drought risk

Water stress score is 6/10 โ€” consider drought-tolerant varieties and mulching

Monthly Watering Guide for Peas

Peas needs approximately 0.7 inches of water per week (3" per month). Here's how your county's rainfall compares month by month.

Month Peas Needs Rainfall You Supplement Action
Jan โ€” 1.4" 0" โ„๏ธ Dormant
Feb โ€” 1" 0" โ„๏ธ Dormant
Mar โ€” 1.6" 0" โ„๏ธ Dormant
Apr โ€” 1.9" 0" โ„๏ธ Dormant
May 3" 2.4" 0.6" ๐Ÿ’ง Light watering
Jun 3" 1.4" 1.6" ๐Ÿšฟ Regular watering
Jul 3" 1.6" 1.4" ๐Ÿ’ง Light watering
Aug 3" 2" 1" ๐Ÿ’ง Light watering
Sep 3" 1.4" 1.6" ๐Ÿšฟ Regular watering
Oct โ€” 1.8" 0" โ„๏ธ Dormant
Nov โ€” 1.3" 0" โ„๏ธ Dormant
Dec โ€” 1.1" 0" โ„๏ธ Dormant

Water needs are for active growing months only (Mayโ€“Sep in Phillips County). Supplement amounts are based on average rainfall โ€” actual needs vary with temperature, soil, and mulching.

Peas Heat Requirements (GDD)

What are Growing Degree Days (GDD)?

Growing Degree Days measure the total warmth your plants receive during the growing season. Think of it as a "heat bank" โ€” every day above 50ยฐF deposits warmth that helps your plants grow.

Each plant needs a certain amount of accumulated heat to mature. If your county provides more GDD than the plant needs, it's a great fit. If it's close, you may want to choose faster-maturing varieties or start seeds indoors to get a head start.

Peas needs ~625 GDD — county provides 1,260 GDD Excellent fit

Peas Planting Timeline โ€” Phillips County, MT

Peas Planting Calendar

Activity When Date Range
Start Indoors April 6 Apr 6 โ€“ Apr 20
Transplant Outdoors May 18 May 18 โ€“ Jun 1
Direct Sow May 11 May 11 โ€“ Jun 1
Harvest July 13 Jul 13 โ€“ Sep 7
Fall Sowing June 29 Jun 29 โ€“ Jul 13

Plant 1" deep ยท 4" apart ยท Rows 18" apart

Month-by-Month Timeline

MonthActivities
January โ€”
February โ€”
March โ€”
April Start Indoors
May Transplant Outdoors Direct Sow
June Transplant Outdoors Direct Sow Fall Sowing
July Fall Sowing Harvest
August Harvest
September Harvest
October โ€”
November โ€”
December โ€”

Growing Conditions

โ˜€๏ธ Sun

Full Sun (6-8+ hours)

๐Ÿ’ง Water

0.7"/week ยท Only during dry spells

๐Ÿ“… Days to Maturity

55โ€“70 days

๐Ÿงช Soil pH

Needs 6โ€“7.5 ยท Your soil: acceptable

๐Ÿ—บ๏ธ USDA Zone

Zone 4a

๐Ÿ“† Growing Season

126 days in Phillips County

Growing Tips for Peas in Phillips County

Direct sow Peas outdoors after May 18 in Phillips County when soil has warmed and frost danger has passed.

Common pests for Peas in this region include bean beetles and aphids. Use row covers early in the season and inspect plants weekly.

General growing tips

Direct sow as early as soil can be worked in spring. Inoculate seeds with rhizobium for best nitrogen fixation. Provide trellising for climbing varieties.

Companion Planting

Good Companions

Avoid Planting Near

  • Onion
  • Garlic

Check more plant combinations with our Companion Planting Checker →

๐ŸŒพ Save Your Own Peas Seeds
Life Cycle Annual
Pollination Self-Pollinating
How to Collect Let pods dry brown and papery on the vine.
Storage Store airtight; viable 3 years at 35ยฐF, under 45% humidity.

Very easy to save. Self-pollinating means varieties stay true.

Frequently Asked Questions

When should I plant Peas in Phillips County, MT?

Phillips County is in Zone 4a with an average last frost of May 18. Plan your Peas planting based on this frost date โ€” see the calendar above for exact timing.

What planting zone is Phillips County, MT?

Phillips County, Montana is in USDA Hardiness Zone 4a. The average last spring frost is May 18 and first fall frost is September 21.

๐ŸŒฑ

Plan Your Garden with Confidence

Get our free Garden Planner โ€” designed to help Phillips County gardeners in Zone 4a organize planting dates, track what's growing, and never miss a planting window.

Get Your Free Garden Planner →

Free download. Plan your entire garden season in minutes.

Data sources: USDA Plant Hardiness Zone Map (2023), NOAA 30-Year Climate Normals. Frost dates are based on 50% probability averages for Phillips County, MT. Local conditions may vary. Last updated: April 2026.